1. Field of the Invention
The present invention relates to power tongs, and more particularly, is directed to a power tong utilizing a rotor assembly providing improved maintenance and operating capabilities and a power tong that is easier to manufacture.
2. Description of the Prior Art
In well-drilling operations, a rotary power tong is used to grip and rotate lengths of pipe or rods which are connected together by threaded end sections. In the usual case, the power tong is of the open-headed type, having a bifurcated housing and cover with a center opening and an outwardly-open passageway or throat which permits the tong to be positioned around a pipe joint without the necessity of lowering the tong over a length of the pipe.
When the tong is operated, pipe-gripping means (often referred to as jaws) are caused to revolve around the aforesaid central opening, these jaws causing the pipe or casing section to rotate. Most tongs accomplish the gripping action of the jaws by means of a rotating rotor assembly which forces a cam attached to the jaw frame to lock into position against a cam surface along the inside surface of the rotor upon initial rotation of the rotor assembly. The action of the cam against the cam surface forces the jaws radially inward causing the jaws to engage the pipe. Continued rotation of the rotor assembly imparts rotation to the jaws and pipe as required.
Typically, the rotors of the prior art devices are rotated on roller assemblies secured within the power tong housing and cover. These roller assemblies were positioned in a generally circular pattern around the generally annular rotor to guide and support the rotor for rotation within the housing. Since the roller assemblies were secured within both the housing and cover, close manufacturing tolerances were required when machining the holes in the housing and cover for securing the roller assemblies in place. If the roller assemblies are not positioned co-axially above and below one another, the rotor can become unbalanced providing for uneven loading and rotation within the housing. An unbalanced rotor can cause premature wear and tear on the respective moving parts of the power tong assembly.
Furthermore, to inspect and lubricate the roller assemblies it is required to remove the housing cover and rotor from the tong which requires lengthy down time and manual labor, resulting in high maintenance costs.
Accordingly, it is an object of the present invention to provide a power tong incorporating a rotor assembly and roller assemblies which provide for a smooth, balanced rotor rotation within the housing to limit the premature wear and tear of the moving parts of the power tong.
Another object of this invention is to provide a power tong wherein the roller assemblies can be lubricated, repaired and/or replaced without removing the housing cover or rotor from the power tong assembly.
Yet another object of this invention is to provide a power tong which is easier to manufacture and at a lower cost than prior art power tong devices.
These, together with other objects and advantages of the invention, will become more apparent upon reading the following specification.